The production of organic compounds using synthesis gas, which is a mixture of carbon monoxide and hydrogen, or from carbon monoxide as one of the reactants has been known for a significant period of time. It is well known that one can produce methanol directly from synthesis gas and that methanol can be further reacted by hydroformylation, homologation and carbonylation reactions to produce acetaldehyde, ethanol and acetic acid or its methyl ester, respectively. It is also known that alcohols, esters, ethers, and other organic compounds can be reacted with synthesis gas or carbon monoxide to produce oxygenated organic compounds. The difficulties, however, have resided in the ability to carry out any one of these chosen reactions to produce the desired compound at acceptable efficiency, conversion rate and selectivity.
In almost all instances the reaction is generally catalyzed using a Group VIII transition metal compound as catalyst and a halogen as the promoter. It is known that many other metal compounds and promoters can be used. In addition, the prior art has disclosed the use of secondary activators or ligands in conjunction with the metal catalysts and promoters. These secondary activators can be other metallic salts or compounds, amines, phosphorus compounds, as well as a multitude of other compounds that have been disclosed in the published literature. Thus, a typical catalyst system contains the metal atom catalyst, promoter and, optionally, ligands, solvents and secondary activators. Though a significant amount of literature does not exist describing the production of ethylidene diacetate, to our knowledge it does not disclose or suggest our invention. Several pertinent references in this area are discussed below.
U.S. Pat. No. 2,555,950, issued on June 5, 1951 and assigned to E. I. duPont de Nemours & Co., discloses the process for reacting a 1,1-dimethoxy ether of an n-alkane with carbon monoxide and hydrogen in the presence of a cobalt hydrogenation catalyst as the sole catalytic agent. At column 3, line 41 et sequentia, the inventors describe the products obtained as being aldehydes or alcohols and specifically identify the products as 2-methoxy-1-propanal, 2-methoxy-1-propanol, 2-methoxy-1-butanal and 2-methoxy-1-butanol. There is no suggestion or disclosure on the use of a rhodium catalyst and lithium iodide or of the production of ethylidene diacetate.
U.S. Pat. No. 4,062,898, issued on Dec. 13, 1977 to M. Dubeck and G. G. Knapp and assigned to Ethyl Corporation, discloses the conversion of lower acetals to alcohols in the presence of a cobalt catalyst which may also contain iodine and ruthenium components. There is no suggestion or disclosure on the use of a rhodium catalyst, nor is there any indication in the patent, including the detailed examples, that ethylidene diacetate was produced or could be produced.
British Patent Specification 1,538,782, issued to N. Rizkalla and C. N. Winnick and published on Jan. 24, 1979 (Belgian equivalent, 839,321) , and the references referred to therein, relate to the preparation of ethylidene diacetate by the reaction of methyl acetate and/or dimethyl ether with carbon monoxide and hydrogen in the presence of a halide and a Group VIII nobel metal catalyst under essentially anhydrous conditions. There is no disclosure or suggestion for the production of ethylidene diacetate from dimethyl acetal.
In European Patent Application No. 0028474A1, filed by T. Isshike et al and published on May 13, 1981, there is disclosed in the process for producing vinyl acetate a step in which acetaldehyde and dimethyl acetal are converted to ethylidene diacetate and methyl acetate using an acid catalyst. The suitable acid catalysts are disclosed on pages 14 to 16 of this publication. The reference contains no mention of the use of rhodium or its compounds in conjunction with lithium iodide nor of the carbonylation of dimethyl acetal with carbon monoxide to form ethylidene diacetate. A similar disclosure on the preparation of ethylidene diacetate from acetals is also shown in Japan Kokai 56-40642/81.
In European Patent Application No. 0028515A1, filed by T. Isshiki and published on May 13, 1981, there is disclosed the production of ethylidene diacetate by the reaction of carbon monoxide with dimethyl acetal, a Group VIII metal compound and an iodide or bromide. The publication makes no distinction as to the Group VIII metal and halide that can be employed with the examples showing the use of rhodium, palladium and nickel and methyl iodide as the sole reactants within the broad definition. The amount of methyl iodide used in the examples ranges from about 20% to about 35% by weight of the initial reactants charged to the reactor; the use of such high concentrations is not commercially acceptable due to its corrosivity and cost. The results reported in the examples of this reference indicate a best rate for production of ethylidene diacetate of about 0.25 mole/liter/hour.
In European Patent Application No. 0035860A2, filed by T. Isshiki and published on Sept. 16, 1981, ethylidene diacetate and/or acetaldehyde are produced by the hydrocarbonylation of methyl acetate or dimethyl ether with carbon monoxide and hydrogen in the presence of a palladium catalyst and a halide promoter. This is not our process. Further, the reference indicates on pages 3 and 4 that rhodium, platinum and ruthenium are poor catalysts.
It can be seen that the prior art contains many disclosures dealing with the catalytic production of ethylidene diacetate, including its production from dimethyl acetal. The art also discloses the production of other organic compounds from synthesis gas.